/*
a permutation of a set is, loosely speaking, an arrangement of its members into a sequence or linear order, or if the set is already ordered, a rearrangement of its elements.
The word "permutation" also refers to the act or process of changing the linear order of an ordered set
More at : https://en.wikipedia.org/wiki/Permutation
*/

const createPermutations = ( str ) => {
  // convert string to array
  const arr = str.split( '' )

  // get array length
  const strLen = arr.length
  // this will hold all the permutations
  const perms = []
  let rest
  let picked
  let restPerms
  let next

  // if strLen is zero, return the same string
  if ( strLen === 0 ) {
    return [ str ]
  }
  // loop to the length to get all permutations
  for ( let i = 0; i < strLen; i++ ) {
    rest = Object.create( arr )
    picked = rest.splice( i, 1 )

    restPerms = createPermutations( rest.join( '' ) )

    for ( let j = 0, jLen = restPerms.length; j < jLen; j++ ) {
      next = picked.concat( restPerms[ j ] )
      perms.push( next.join( '' ) )
    }
  }
  return perms
}

console.log( createPermutations( 'abc' ) ) // should print ["abc", "acb", "bac", "bca", "cab", "cba"]
